Core Shell Nanostructure: Impregnated Activated Carbon as Adsorbent for Hydrogen Sulfide Adsorption

Adsorption-Desorption Behavior of Hydrogen Sulfide Capture on a Modified Activated Carbon Surface

Metal-based adsorbents with varying active phase loadings were synthesized to capture hydrogen sulfide (H₂S) from a biogas mimic system. The adsorption-desorption cycles were implemented to ascertain the H₂S captured. All prepared adsorbents were evaluated by nitrogen adsorption, Brunauer-Emmett-Teller surface area analysis, scanning electron microscopy-energy-dispersive X-ray spectroscopy, and Fourier transform infrared spectroscopy. From the results, modified adsorbents, dual chemical mixture (DCM) and a core-shell (CS) had the highest H₂S adsorption performance with a range of 0.92-1.80 mg H₂S/g. After several cycles of heat/N₂ regeneration, the total H₂S adsorption capacity of the DCM adsorbent decreased by 62.1%, whereas the CS adsorbent decreased by only 25%. Meanwhile, the proposed behavioral model for H₂S adsorption-desorption was validated effectively using various analyses throughout the three cycles of adsorption-desorption samples. Moreover, as in this case, the ZnAc₂/ZnO/CAC_OS adsorbents show outstanding performances with 30 cycles of adsorption-desorption compared to only 12 cycles of ZnAc₂/ZnO/CAC_DCM. Thus, this research paper will provide fresh insights into adsorption-desorption behavior through the best adsorbents' development and the adsorbents' capability at the highest number of adsorption-desorption cycles.

Performance and Characterization of Bi-Metal Compound on Activated Carbon for Hydrogen Sulfide Removal in Biogas

This study reports on the synthesis of bi-metal compound (BMC) adsorbents based on commercial coconut activated carbon (CAC), surface-modified with metal acetate (ZnAc₂), metal oxide (ZnO), and the basic compounds potassium hydroxide (KOH) and sodium hydroxide (NaOH). The adsorbents were then characterized by scanning electron microscopy and elemental analysis, microporosity analysis through Brunauer-Emmett-Teller (BET) analysis, and thermal stability via thermogravimetric analysis. Adsorption-desorption test was conducted to determine the adsorption capacity of H₂S via 1 L adsorber and 1000 ppm H₂S balanced 49.95% for N₂ and CO₂. Characterization results revealed that the impregnated solution homogeneously covered the adsorbent surface, morphology, and properties. The adsorption test result reveals that the ZnAc₂/ZnO/CAC_B had a higher H₂S breakthrough adsorption capacity and performed at larger than 90% capability compared with a single modified adsorbent (ZnAc₂/CAC). Therefore, the synthesized BMC adsorbents have a high H₂S loading, and the abundance and low cost of CAC may lead to favorable adsorbents in H₂S captured.

Effect of Bimetallic-Activated Carbon Impregnation on Adsorption-Desorption Performance for Hydrogen Sulfide (H2S) Capture

This study reports on the impregnation of bi-metallic adsorbents based on commercial coconut activated carbon (CAC), surface-modified with metal acetate (ZnAc₂), metal oxide (ZnO and TiO₂), and the basic compound potassium hydroxide (KOH). The morphology of the adsorbents was then characterized with SEM-EDX, the microporosity was determined using Brunauer-Emmett-Teller (BET) analysis, the thermal stability was investigated via thermogravity analysis (TGA), and functional group analysis was undertaken with Fourier-transform infrared (FTIR) spectroscopy. These modified adsorbents were subjected to a real adsorption test for H₂S capture using a 1 L adsorber with 5000 ppm H₂S balanced for N₂, with temperature and pressure maintained at an ambient condition. Adsorption-desorption was carried out in three cycles with the blower temperature varied from 50 °C to 150 °C as the desorption condition. Characterization results revealed that the impregnated solution homogeneously covered the adsorbent surface, effecting the morphology and properties. Based on this study, it was found that ZnAc₂/TiO₂/CAC_DCM showed a significant increase in adsorption capacity with the different temperatures applied for the desorption in the second cycle: 1.67 mg H₂S/g at 50 °C, 1.84 mg H₂S/g at 100 °C, and 1.96 mg H₂S/g at 150 °C. ZnAc₂/ZnO/CAC_DCM seemed to produce the lowest percentage of degradation in the three cycles for all the temperatures used in the adsorption-desorption process. Therefore, ZnAc₂/ZnO/CAC_DCM has the potential to be used and commercialized for biogas purification for H₂S removal.